A variety of biopsy needles and similar devices for obtaining a tissue sample from a patient are known. Commonly, such devices include a thin needle or stylet that can be inserted into the skin of the patient near the location of tissue to be sampled, such as suspected malignancies or other tissue of interest. Once the distal end or other cutting portion of the needle or stylet is within the tissue of interest, a portion of the tissue is excised and captured. The needle or stylet is withdrawn with the tissue sample, which can be retrieved from the device and studied.
Such products have proven quite effective in obtaining tissue in a minimally-invasive manner and with minimal discomfort to the patient. Their lightweight, low-cost nature, combined with their ease of operation and reusability, make them excellent for sampling tissue that may present or indicate a health problem to the patient.
Most biopsy needles have only one sample size setting for each needle, and in many cases that setting is either for a length of sample of 10 mm or 20 mm. There are often cases where the physician or other clinician does not know which sample size is appropriate for the given patient. Having estimated that a 10 mm length of sample will do, a clinician might decide after a few such 10 mm samples that he or she may need to obtain more tissue to retrieve an adequate, testable sample. He or she would then have to dispose of the used 10-mm-sample biopsy needle and replace it with a new 20-mm-sample needle. This is inconvenient, and introduces additional discomfort to that patient and cost for supplies for the overall procedure.
Thus, if the tissue of interest is easily findable and of a size easily determined by the clinician, then he or she can choose a product that will provide the amount of tissue suggested by the patient's situation. However, in other cases there may be less certainty, meaning that the clinician may make an ultimately incorrect estimate of how much tissue to obtain, and therefore may have to use multiple biopsy devices to obtain samples of differing lengths or amounts. Further, hospitals, clinics and other health service providers must stock multiple versions of biopsy needles to be sure of having a product suited to particular needs. There remains a need for tissue sampling devices capable of obtaining varying amounts of tissue while maintaining the ease of use of the device.